OFFSET
1,1
COMMENTS
Apart from the first term, odd primes p such that (-17/p) = 1 and x^4 - x^2 = 4 has a solution mod p. - Charles R Greathouse IV, Nov 11 2012
All terms are in {1, 9, 13, 17, 21, 25, 33, 49, 53} mod 68, but this not sufficient for inclusion. - Charles R Greathouse IV, Nov 11 2012
REFERENCES
David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989.
LINKS
Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
QuadPrimes2[1, 0, 17, 10000] (* see A106856 *)
PROG
(PARI) is(n)=if(kronecker(17, n)>0 && kronecker(-17, n)>0 && n>2 && isprime(n), kronecker(lift((1+sqrt(Mod(17, n)))/2), n)>0, n==17) \\ Charles R Greathouse IV, Nov 11 2012
(Magma) /* By first comment: */ [17] cat [p: p in PrimesInInterval(3, 2200) | LegendreSymbol(-17, p) eq 1 and exists{x: x in ResidueClassRing(p) | x^4-x^2 eq 4}]; // Bruno Berselli, Nov 11 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved